<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <!-- 表单容器：form标签 -->
    <form action="">
        <label for="username">用户名</label>
        <input type="text" name="" id="username" placeholder="用户名">
        <label for="password">密码</label>
        <input type="password" name="" id="password" placeholder="密码">
        <label for="">男</label>
        <input name="sex" type="radio">
        <label for="">女</label>
        <input name="sex" type="radio">
        <select name="" id="">
            <option value="">男</option>
            <option value="">女</option>
        </select>
        <input type="checkbox">
        <input type="checkbox">
        <input type="submit" value="登陆">
        <input type="button" value="按钮">
    </form>
</body>
</html>